Alien is a 1979 science-fiction horror film directed by Ridley Scott, and starring Tom Skerritt, Sigourney Weaver, Veronica Cartwright, Harry Dean Stanton, John Hurt, Ian Holm and Yaphet Kotto. The film's title refers to a highly aggressive extraterrestrial creature that stalks and kills the crew of a spaceship. Dan O'Bannon wrote the screenplay from a story he wrote with Ronald Shusett, drawing influence from previous works of science fiction and horror. The film was produced through Brandywine Productions and distributed by 20th Century Fox, with producers David Giler and Walter Hill making significant revisions and additions to the script. The titular Alien and its accompanying elements were designed by Swiss surrealist artist H. R. Giger, while concept artists Ron Cobb and Chris Foss designed the human aspects of the film.
The commercial towing spaceship Nostromo, owned and operated by the Earth mega-corporation Weyland-Yutani, is on a return trip to Earth hauling a refinery and twenty million tons of mineral ore, with a seven-member crew in stasis. Detecting a transmission of unknown origin from a nearby planetoid, the ship's computer awakens the crew. Acting on standing orders from their corporate employers, they set out to investigate the transmission's source. The Nostromo lands on the planetoid, and Captain Dallas (Tom Skerritt), Executive Officer Kane (John Hurt), and Navigator Lambert (Veronica Cartwright) set out to investigate the signal, leaving Warrant Officer Ripley (Sigourney Weaver), Science Officer Ash (Ian Holm), and Engineers Brett (Harry Dean Stanton) and Parker (Yaphet Kotto) behind on the ship.
Dallas, Kane, and Lambert discover that the signal is coming from a derelict alien spacecraft. Inside they find the remains of a large alien creature whose ribs appear to have been broken outward from the inside. Meanwhile, Ripley determines that the transmission is actually some type of warning rather than a distress signal. Kane discovers a vast chamber containing thousands of eggs, one of which releases a creature that attaches to his face. Rendered unconscious, Kane is carried back to the Nostromo. Acting on improper orders from Dallas, Ash violates quarantine protocol by opening the airlock, allowing the exploratory team aboard. After an unsuccessful attempt by Ash to surgically remove the creature from Kane's face, the crew discover that the creature's blood contains a corrosive acid. The creature eventually detaches from Kane's face by itself and is later found dead. The Nostromo leaves the planet and resumes its trip to Earth.
Kane awakens from his ordeal with some memory loss but no other apparent ill effects. During the crew's final dinner before re-entering hypersleep, he chokes and convulses until an alien creature bursts from his chest, killing him and escaping into the ship. Lacking conventional weapons, the crew attempt to locate and capture the creature by fashioning motion trackers, electric prods, and flamethrowers. The Alien, which has now grown into an eight foot creature, attacks Brett and disappears with his body into an airshaft. Dallas enters the airshaft network intending to force the Alien into an airlock, but it ambushes him. When the others find no trace of Dallas, Lambert implores the remaining crew members to escape in the ship's shuttle, but Ripley, now in command, explains that the shuttle will not support four people, and that they should continue with Dallas' plan of cornering and flushing out the Alien.
Accessing the ship's computer, Ripley discovers that Ash has been ordered to return the Alien to the Nostromos corporate employers even at the expense of the crew's lives. Ash attacks her, but Parker and Lambert intervene, decapitating and impaling Ash, revealing him to be an android. Before being destroyed, Ash predicts that the others will not survive. The remaining three crew members plan to arm the Nostromos self-destruct mechanism and escape in the shuttle, but Parker and Lambert are killed by the Alien while gathering the necessary coolant supplies. Ripley initiates the self-destruct sequence herself and heads for the shuttle with the crew's cat, but finds the Alien blocking her way. She unsuccessfully attempts to abort the self-destruct, then returns to find the Alien gone and narrowly escapes in the shuttle as the Nostromo explodes.
As she prepares to enter stasis, Ripley discovers that the Alien has hidden aboard the shuttle. She puts on a spacesuit and opens the hatch, causing explosive decompression which forces the Alien to the open doorway. She propels it out by shooting it with a grappling hook, but the gun catches in the closing door, tethering the Alien to the shuttle. As it attempts to crawl into one of the engines, Ripley activates them and blasts the alien into space. She then puts herself and the cat into stasis and resumes the voyage back home.
- Bolaji Badejo as The Alien. A Nigerian design student, Badejo was discovered in a bar by a member of the casting team, who put him in touch with Ridley Scott. Scott believed that Badejo, at 7 feet 2 inches (218 cm) and with a slender frame, could portray the Alien and look as if his arms and legs were too long to be real, creating the illusion that there could not possibly be a human being inside the costume.Stuntmen Eddie Powell and Roy Scammell also portrayed the Alien in some scenes.
- Veronica Cartwright as Lambert, the Nostromo's navigator. Cartwright had previous experience in horror and science fiction films, having acted in The Birds (1963) and Invasion of the Body Snatchers (1978). She originally read for the role of Ripley, and was not informed that she had instead been cast as Lambert until she arrived in London for wardrobe. She disliked the character's emotional weakness, but nevertheless accepted the role: "They convinced me that I was the audience's fears; I was a reflection of what the audience is feeling."Cartwright won a Saturn Award for Best Supporting Actress for her performance.
- Ian Holm as Ash, the ship's Science Officer who is revealed to be an android under orders to bring the Alien back to the Nostromo's corporate employers. Holm, a character actor who by 1979 had already been in twenty films, was the most experienced actor cast for Alien.
- John Hurt as Kane, the Executive Officer who becomes the host for the Alien. Hurt was Scott's first choice for the role but was contracted on a film in South Africa during Alien's filming dates, so Jon Finch was cast as Kane instead. However, Finch became ill during the first day of shooting and was diagnosed with severe diabetes, which had also exacerbated a case of bronchitis. Hurt was in London by this time, his South African project having fallen through, and he quickly replaced Finch. His performance earned him a nomination for a BAFTA Award for Best Actor in a Supporting Role.
- Yaphet Kotto as Parker, the Chief Engineer. Kotto, an African American, was chosen partly to add diversity to the cast and give the Nostromo crew an international flavor. Kotto was sent a script off the back of his recent success with Live and Let Die, although it was some time and deliberation between Kotto and his agent before he was offered the part.
- Tom Skerritt as Dallas, the Captain of the Nostromo. Skerritt had been approached early in the film's development but declined as it did not yet have a director and had a very low budget. Later, when Scott was attached as director and the budget had been doubled, Skerritt accepted the role of Dallas.
- Harry Dean Stanton as Brett, the Engineering Technician. Stanton's first words to Scott during his audition were "I don't like sci fi or monster movies." Scott was amused and convinced Stanton to take the role after reassuring him that Alien would actually be a thriller more akin to Ten Little Indians.
- Sigourney Weaver as Ripley, the warrant officer aboard the Nostromo. The decision to make the lead character a woman was made by Giler and Hill, who felt this would help Alien stand out in the otherwise male-dominated genre of science fiction. Weaver, who had Broadway experience but was relatively unknown in film, impressed Scott, Giler, and Hill with her audition. She was the last actor to be cast for the film, and performed most of her screen tests in-studio as the sets were being built. The role of Ripley was Weaver's first leading role in a motion picture, and earned her nominations for a Saturn Award for Best Actress and a BAFTA award for Most Promising Newcomer to Leading Film Role.
To assist the actors in preparing for their roles, Ridley Scott wrote several pages of backstory for each character explaining their histories. He filmed many of their rehearsals in order to capture spontaneity and improvisation, and tensions between some of the cast members, particularly towards the less-experienced Weaver, translated convincingly on film as tension between their respective characters.
Film critic Roger Ebert notes that the actors in Alien were older than was typical in thriller films at the time, which helped make the characters more convincing: None of them were particularly young. Tom Skerritt, the captain, was 46, Hurt was 39 but looked older, Holm was 48, Harry Dean Stanton was 53, Yaphet Kotto was 42, and only Veronica Cartwright at 30 and Weaver at 29 were in the age range of the usual thriller cast. Many recent action pictures have improbably young actors cast as key roles or sidekicks, but by skewing older, Alien achieves a certain texture without even making a point of it: These are not adventurers but workers, hired by a company to return 20 million tons of ore to Earth. David McIntee, author of Beautiful Monsters: The Unofficial and Unauthorised Guide to the Alien and Predator Films, notes that part of the film's effectiveness in frightening viewers "comes from the fact that the audience can all identify with the characters...Everyone aboard the Nostromo is a normal, everyday, working Joe just like the rest of us. They just happen to live and work in the future.